docs: def in_(self, *objs):
          """
          Create a condition
          """
          if not objs:
              return self.table.c[self.fielda]!=self.table.c[self.fielda]
          else:
              keys = get_objs_columns(objs, self.reference_fieldname)
              sub_query = select([self.table.c[self.fielda]], (self.table.c[self.fieldb] == self.reference_class.c[self.reference_fieldname]) & (self.table.c[self.fieldb].in_(keys)))
              condition = self.model_class.c[self.reversed_fieldname].in_(sub_query)
              return condition